Checking ceiling insulation

It's worth checking your insulation occasionally to ensure it is still working effectively. It may never have been up to today’s standard, may have been damaged by people working in the ceiling space or slumped towards a heat source, creating a fire risk.

Watch: How to check your ceiling insulation | 2:36 min

DIY insulation check

If you can do it safely, get a step-ladder and peek through the hatch of your ceiling into your roof space to see if you have insulation.

You will need to add a top-up layer of insulation, if your existing insulation:

is less than 12cm thick (it should be thicker than the height of the ceiling joists)

doesn't cover the whole ceiling

has gaps in it, or places where it is squashed or tucked in.

You need to remove the old insulation and start again with a new layer, if:

Recessed downlights NOT marked either CA80, CA90, CA135, IC, IC-F or IC-4 (look for a label on top). This generally includes all downlights installed before mid-2012, but may also apply to some downlights that have been installed more recently.

Recessed downlights marked either CA80, CA90, CA135 (look for a label on top)

Compatible bulk insulation can touch the sides of the downlight, but must not cover it. Loose-fill insulation typically requires a guard or barrier to prevent it from getting in direct contact with the downlight.

Recessed downlights marked either IC, IC-F or IC-4 (look for a label on top)

Compatible bulk insulation can cover the downlight. Loose-fill insulation typically requires a guard or barrier to prevent it from getting in direct contact with the downlight.

Downlight transformers, ballasts and drivers

Must be either placed on top of insulation or require a 50mm minimum gap.

3-in-1 fan/heat/light units

100mm

Other lamps in the roof space

200mm

Unducted extractor fans and rangehoods (insulation can get trapped in these, causing the motor to overheat)

200mm

Ducted extractor fans and rangehoods

50mm to electrical compoonents (e.g. fan motor)

Brick or concrete chimneys

50mm

Metal chimneys or flues

75mm

Refer to New Zealand Standard NZS 4246:2016 Appendix A for full details of the requirements.

If you have loose-fill insulation, you should use permanently fixed collars made of fire-resistant materials. The collars should extend at least 75mm above the insulation layer.